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><H1
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><A
NAME="INFOSCHEMA-ELEMENT-TYPES"
>34.22. <TT
CLASS="LITERAL"
>element_types</TT
></A
></H1
><P
>   The view <TT
CLASS="LITERAL"
>element_types</TT
> contains the data type
   descriptors of the elements of arrays.  When a table column,
   domain, function parameter, or function return value is defined to
   be of an array type, the respective information schema view only
   contains <TT
CLASS="LITERAL"
>ARRAY</TT
> in the column
   <TT
CLASS="LITERAL"
>data_type</TT
>.  To obtain information on the element
   type of the array, you can join the respective view with this view.
   For example, to show the columns of a table with data types and
   array element types, if applicable, you could do:
</P><PRE
CLASS="PROGRAMLISTING"
>SELECT c.column_name, c.data_type, e.data_type AS element_type
FROM information_schema.columns c LEFT JOIN information_schema.element_types e
     ON ((c.table_catalog, c.table_schema, c.table_name, 'TABLE', c.dtd_identifier)
       = (e.object_catalog, e.object_schema, e.object_name, e.object_type, e.collection_type_identifier))
WHERE c.table_schema = '...' AND c.table_name = '...'
ORDER BY c.ordinal_position;</PRE
><P>
   This view only includes objects that the current user has access
   to, by way of being the owner or having some privilege.
  </P
><DIV
CLASS="TABLE"
><A
NAME="AEN46223"
></A
><P
><B
>Table 34-20. <TT
CLASS="LITERAL"
>element_types</TT
> Columns</B
></P
><TABLE
BORDER="1"
CLASS="CALSTABLE"
><COL><COL><COL><THEAD
><TR
><TH
>Name</TH
><TH
>Data Type</TH
><TH
>Description</TH
></TR
></THEAD
><TBODY
><TR
><TD
><TT
CLASS="LITERAL"
>object_catalog</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>       Name of the database that contains the object that uses the
       array being described (always the current database)
      </TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>object_schema</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>       Name of the schema that contains the object that uses the array
       being described
      </TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>object_name</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>       Name of the object that uses the array being described
      </TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>object_type</TT
></TD
><TD
><TT
CLASS="TYPE"
>character_data</TT
></TD
><TD
>       The type of the object that uses the array being described: one
       of <TT
CLASS="LITERAL"
>TABLE</TT
> (the array is used by a column of
       that table), <TT
CLASS="LITERAL"
>DOMAIN</TT
> (the array is used by
       that domain), <TT
CLASS="LITERAL"
>ROUTINE</TT
> (the array is used by
       a parameter or the return data type of that function).
      </TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>collection_type_identifier</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>       The identifier of the data type descriptor of the array being
       described.  Use this to join with the
       <TT
CLASS="LITERAL"
>dtd_identifier</TT
> columns of other information
       schema views.
      </TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>data_type</TT
></TD
><TD
><TT
CLASS="TYPE"
>character_data</TT
></TD
><TD
>       Data type of the array elements, if it is a built-in type, else
       <TT
CLASS="LITERAL"
>USER-DEFINED</TT
> (in that case, the type is
       identified in <TT
CLASS="LITERAL"
>udt_name</TT
> and associated
       columns).
      </TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>character_maximum_length</TT
></TD
><TD
><TT
CLASS="TYPE"
>cardinal_number</TT
></TD
><TD
>Always null, since this information is not applied to array element data types in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>character_octet_length</TT
></TD
><TD
><TT
CLASS="TYPE"
>cardinal_number</TT
></TD
><TD
>Always null, since this information is not applied to array element data types in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>character_set_catalog</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>Applies to a feature not available in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>character_set_schema</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>Applies to a feature not available in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>character_set_name</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>Applies to a feature not available in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>collation_catalog</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>Not yet implemented</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>collation_schema</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>Not yet implemented</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>collation_name</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>Not yet implemented</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>numeric_precision</TT
></TD
><TD
><TT
CLASS="TYPE"
>cardinal_number</TT
></TD
><TD
>Always null, since this information is not applied to array element data types in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>numeric_precision_radix</TT
></TD
><TD
><TT
CLASS="TYPE"
>cardinal_number</TT
></TD
><TD
>Always null, since this information is not applied to array element data types in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>numeric_scale</TT
></TD
><TD
><TT
CLASS="TYPE"
>cardinal_number</TT
></TD
><TD
>Always null, since this information is not applied to array element data types in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>datetime_precision</TT
></TD
><TD
><TT
CLASS="TYPE"
>cardinal_number</TT
></TD
><TD
>Always null, since this information is not applied to array element data types in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>interval_type</TT
></TD
><TD
><TT
CLASS="TYPE"
>character_data</TT
></TD
><TD
>Always null, since this information is not applied to array element data types in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>interval_precision</TT
></TD
><TD
><TT
CLASS="TYPE"
>character_data</TT
></TD
><TD
>Always null, since this information is not applied to array element data types in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>domain_default</TT
></TD
><TD
><TT
CLASS="TYPE"
>character_data</TT
></TD
><TD
>Not yet implemented</TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>udt_catalog</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>       Name of the database that the data type of the elements is
       defined in (always the current database)
      </TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>udt_schema</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>       Name of the schema that the data type of the elements is
       defined in
      </TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>udt_name</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>       Name of the data type of the elements
      </TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>scope_catalog</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>Applies to a feature not available in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>scope_schema</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>Applies to a feature not available in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>scope_name</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>Applies to a feature not available in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>maximum_cardinality</TT
></TD
><TD
><TT
CLASS="TYPE"
>cardinal_number</TT
></TD
><TD
>Always null, because arrays always have unlimited maximum cardinality in <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
></TD
></TR
><TR
><TD
><TT
CLASS="LITERAL"
>dtd_identifier</TT
></TD
><TD
><TT
CLASS="TYPE"
>sql_identifier</TT
></TD
><TD
>       An identifier of the data type descriptor of the element.  This
       is currently not useful.
      </TD
></TR
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